The disclosure relates to a motor drive control apparatus, a motor drive control method and a program of the same.
Traditionally, in a drive motor or generator disposed as a motor machine, a rotor is rotatably disposed which has a magnetic pole pair formed of north- and south-pole permanent magnets, and a stator is disposed in the outward radial direction from the rotor. The stator has coils of U-phase, V-phase, and W-phase.
A motor drive apparatus and a motor drive control apparatus which controls the motor drive apparatus are provided in order to drive the drive motor or the generator to generate drive motor torque, which is the torque of the drive motor, or generator torque, which is the torque of the generator. A drive motor control unit is provided which drives the drive motor and a generator control unit is provided which drives the generator and each constitutes a motor machine control unit. Asynchronous pulse width modulation (PWM) signals of U-phase, V-phase, and W-phase generated in the motor machine control unit are sent to an inverter, and phase currents generated in the inverter, that is, the currents in U-phase, V-phase, and W-phase, are fed to the individual stator coils for asynchronous PWM control which generates the drive motor torque or the generator torque.
In the asynchronous PWM control, when the asynchronous PWM signals in the individual phases are generated, voltage in the individual phases is applied to each of the stator coils. In the area where low voltage is applied, the asynchronous PWM signal is generated in a sine wave PWM pattern, whereas in the overmodulation area where the voltage becomes high, i.e., the sine wave peak exceeds the battery voltage, the asynchronous PWM signal is generated in an overmodulated PWM pattern. In this case, the amplitude of voltage in the individual phases that can be applied to each of the stator coils has an upper limit. When the voltage to be applied exceeds the upper limit, voltage command value computation cannot follow the variation in the current command value in proportional integral computing, causing vibrations in the voltage command value required a overmodulated PWM pattern.
In addition, switching timing by transistors of the inverter is not synchronous with the voltage phase angle indicative of the phase of the voltage command value. Thus, when the drive motor is to be driven in the high-speed rotation area, vibrations are generated in the voltage in the individual phases, leading to a beat phenomenon.
Therefore, switching between the asynchronous PWM control and synchronous PWM control, for example, rectangular wave voltage control is allowed. The asynchronous PWM signal is generated in a sine wave PWM pattern or in an overmodulated PWM pattern in the medium-speed rotation area or low-speed rotation area for the asynchronous PWM control, and the synchronous PWM signal is generated in a one-pulse pattern with a single pulse in the high-speed rotation area for the rectangular wave voltage control as found in, for example, JP-A-06-078558.
When the synchronous PWM signal is generated in the one-pulse pattern in the rectangular wave voltage control, a voltage can be applied as it exceeds the upper limit of the amplitude of voltage, but an impulse is generated in the motor drive apparatus due to a harmonic component contained in the synchronous PWM signal in the one-pulse pattern when the asynchronous PWM control is switched to the rectangular wave voltage control in the one-pulse pattern.
In switching from the asynchronous PWM control to the rectangular wave voltage control, the synchronous PWM signal is generated in a five-pulse pattern where a harmonic component is small, the synchronous PWM signal is subsequently generated in a three-pulse pattern where a harmonic component is small in the high-voltage area, and then the synchronous PWM signal is generated in a one-pulse pattern.